there are a number of schools in hk, i would recommend going around and trying them out before u decide. namely impakt, kontact, grips, gracie barra, hk bjj, kylin bjj (they will all come up if u google)
i also know someone who can do freelance bjj (brown belt) & mma. let me know if u're interested.

I do not know of a specific place but if you walk into a gym over there and say your style is better then thiers I am sure you will get a good workout. Now when you are in China you can not just challenge someone in a gym there are specific formalities you must follow:
1) You must talk then move your lips while not saying anything. I learned this from watching black belt theater on saturday mornings and that is how all the people speak to each other.
2) You must kill the master so the student can go live in the woods and train by carrying water around.
3) if you go train in the woods, some really hot chick must take you in and help you get better while trainnig for your revenge match.
4) You must learn how to fly from tree to tree and punch and kick oppenents while flying past them.
5) When you are the gym fighting, usually you have to warm up by fighting about 20 students all armed with swords before you get to fight the master.
I hope this helps you with training over there. Good luck. :)